1. Field of the Invention
The invention relates to the field of sorting/collating devices. Particularly, sorting devices for generating collated sets of copies from a set of original documents.
2. Prior Art
The use of a document reproduction system incorporating a high speed copy processor, a copy collator-unloader module with optional stapler and a document handler module for generating collated sets of copies from an original set is well known in the prior art. A set or pile of original documents to be copied is placed in a document tray. The document handler automatically feeds original documents to be copied in seriatim from the pile onto the document platen of the processor. The processor makes copies from the original document. The original document is then returned to the document tray for removal or for recirculation. The copies outputted from the processor are collated into individual sets by the copy sorter-stapler module. If the copy sorter-unloader module is a multiple bin collator, each set is placed in a bin of the collator. The collated set is removed by an operator or if the sorter includes an automatic unloader and stapler, the sets are removed by the automatic unloader and optionally stapled by the stapler.
A particular problem which is associated with the above type of reproducing system is that of bin overflow. The bin overflow is an error condition which occurs when the number of originals or the number of copies required is greater than the capacity of the bin. Since most of the modern reproducing systems are automatic and high speed, there is a need for an error recovery apparatus and method which is automatic and correct an overflow error condition in a relative short time interval.
Thus U.S. Pat. No. 4,134,672 discloses a method and apparatus for recovering from an overflow condition in a single bin copier finisher system. The copier finisher system consists of a copier for reproducing copies from original documents. An intermediate tray is mounted to the copier. Copies which are generated by the copier are loaded into the tray. A finisher including an automatic unloader and a stapler access the intermediate tray to remove copies therefrom. The copies are stapled together to form a set. The set is then loaded onto an output tray. When the number of originals in a particular job is greater than the capacity of the intermediate tray, the job is divided into at least two runs. In the first run, the number of copies made is equivalent to the capacity of the intermediate tray. The automatic unloader then removes the copies generated in the first run and places them on the output tray. In a similar manner, copies generated from subsequent runs but for the same job are fetched from the intermediate tray and placed on the output tray until a set of copies equivalent to the original set is made.
Another prior art example of a bin overflow problem is addressed by U.S. Pat. No. 4,134,581. The associated problem is that the number of sheets in an original set of documents are greater than the capacity of the bins of a multibin collator connected to a copier. Once the number of copy sets are known, the bins of the collator are configured into so-called virtual bins. Each virtual bin includes at least two actual bins. As such, the virtual bin extends the capacity of an actual bin so that collated sets of copies are formed in the virtual bins. One limitation associated with the virtual bin approach is that the number of copy sets should be at least smaller than the number of bins in the multibin collator and preferably smaller than one half the number of bins.